Hybrid cables are utilized in a wide variety of applications that require the transmission of both power and communication signals. Various applications require hybrid cables to be installed in premises, indoor/indoor environments, outdoor or outside plant (“OSP”) locations, buried locations, aerial locations, and/or vertical rise locations. Each of these locations expose cables to different environmental conditions and are subject to different standards and/or requirements. For example, outdoor applications (including OSP, buried, aerial, vertical rise, etc.) subject a cable to a wide range of temperature requirements, wet conditions, high wind shear conditions, and/or other conditions. Many cable standards include requirements associated with environmental conditions that a cable may be subjected to, such as sunlight resistance requirements, temperature requirements, and/or water penetration or water blocking requirements. There is an opportunity for improved hybrid cables that are suitable for use in a wide variety of applications.
In order to satisfy water blocking standards, cables typically must include means to mitigate the transmission of moisture through the cables to avoid decay in communication performance and possible power loss. Traditional techniques for satisfying water penetration requirements include the use of gel-filled cables that incorporate oil-based filling compounds in the core of a cable and, more recently, the use of dry cables that incorporate moisture absorbing materials, such as aramid yarns. Although dry cables are typically easier to handle during installation, these cables are more susceptible to mechanical stresses (e.g., wind shear, etc.) as they lack the cushioning effect realized by gel-filled cables. Additionally, it is often difficult to produce dry fiber optic or composite cables with an appropriate excess fiber length, especially for vertical applications in which seasonal temperature fluctuations could affect fiber performance.
Although conventional gel-filled cables provide improved mechanical support over dry cables, conventional gels or filling materials are often adversely affected by environmental conditions in certain applications, such as vertical rise applications. Vertical towers, such as cell towers, often utilize vertical rise cables to deliver power and/or communications signals to equipment, and the design of a vertical rise cable typically takes a number of factors into consideration, including ease of deployment, the length of the vertical rise, and environmental conditions. In vertical rise applications, elevation, wind, and temperature extremes challenge the rheological properties of conventional oil-based gels. These conditions may translate into stresses that are above the yield of traditional gels, causing the gels to flow towards the bottom of an installed cable (e.g., into a termination cabinet). Accordingly, there is an opportunity for improved hybrid cables suitable for use in multiple applications including vertical rise applications. There is also an opportunity for improved hybrid cables that incorporate a low density filling compound.